I (think I) made a ConAsm UTF-8 decoder. It can decode a 1-4 byte UTF-8-encoded codepoint in 14 cycles. I posted it on my blog with some additional context and my thoughts if you’re interested. Also here’s a GitHub Gist with just the code if you want that. I decided to forgo the forum because I wanted to be able to update it as I get feedback and so I had better formatting options.